Biotechnology to Improve Shelf Life and Quality Traits of Foods - Food Shelf Life Stability: Chemical, Biochemical, and Microbiological Changes - page 320

TABLE 10.2 (continued)
Biotechnological Procedures Commercially Available to Improve Shelf Life
and Quality Traits of Foods

Product Technology Applied Benefit Ref.

Sunflower,
canola

Application of recently acquired
Allelix technology

Altered fatty acid composition and
more nutritious oils with lower
saturated fat content

4, 6

Tobacco Genetically engineered Production of immunoglobulins, not

contaminated by human pathogens

12

Tomatoes Expression of antisense RNA for 1-

aminocyclopropane-1-carboxylic
acid (ACC) synthase which blocks
ethylene production

Slow ripening of tomatoes which stay
green, firm, and unflavored until
exposed to exogenous ethylene

16

Expression of new genes, traditional
bleeding, somoclonal variation,
and RFLP analysis

High solids and high viscosity
(pectin); less cooking for canned
products: paste, catsup, etc.

4, 16,
17

Expression of antisense RNA for
polygalacturonase which would
otherwise degrade pectin

Slow softening of tomatoes which can
vine ripen and stay more firm in
shipment or in home storage

4, 6,
12, 17

Somoclonal variation Ripening of “breaker” tomatoes

continues after harvesting without
ethylene

4

Rearrange or duplicate existing
genes

Control rate of softening, color, and
flavor balance

18

Classical breeding with wild tomato
Lycopersicon cheesmanii

Increase vitamin A 30 times 17

Tomato,
lettuce

Transference of a gene for monellin Sweetness enhancement 9, 19

and deterioration occurs. These physiological changes of respiration, transpiration,
and biosynthesis are affected by intrinsic (i.e., climacteric vs. nonclimacteric com-
modities) and extrinsic (i.e., temperature, ethylene, O 2 , and CO 2 concentration)
factors, but in general they cause quality decline and limit the shelf life of fruits and
vegetables. 2,20 Other types of deterioration, besides physiological, may also occur in
fruits and vegetables. Chemical and enzymatic changes may cause tissue softening,
off-flavors, pigment loss and off-colors, and an overall decline in nutritional value
and taste. Similar effects are produced by physical damage, which is the result of
improper harvesting, handling, processing, or packaging. Microbial deterioration
also contributes significantly to quality decline and may have important safety
implications for some products. Fruits and vegetables are prone to attack by macro-
organisms (i.e., insects, rodents), which further promote deteriorative changes and
quality decline.
The shelf life and availability of fruits and vegetables are limited by the factors
cited previously. To extend the shelf life of fresh fruit and vegetables, transpiration
and respiration rates must be reduced, which can be accomplished by minimizing